package main

import "fmt"

func main(){
	const PI = 3.14
	fmt.Println("请输入半径:")
	var r float64
	fmt.Scan(&r)
	fmt.Println(&r)
	fmt.Println(r)

    area := PI*r*r;
    p := 2*PI*r;

    fmt.Printf("面积是%.2f\n",area)
    fmt.Printf("周长是%.2f\n",p)

}